The introduction of wireless LAN connectivity has created a demand for compact low-cost antennas covering the frequency bands 2.4-2.5 GHz and 4.9-5.9 GHz. These are typically fitted to laptop computers and PDAs, and they will soon be found in printers, scanners and other peripheral devices.
The essential properties for these antennas are high efficiency, and radiation patterns which are as nearly omnidirectional as possible—even when mounted on the target device. These electrical parameters must be combined with physically small dimensions and the potential for production at very low cost. Most antennas will be directly connected to a sub-miniature coaxial cable and the antenna design must embody a suitable means of attachment that will control the placement of the cable accurately enough to ensure good repeatability of input matching.